1. Field of the Invention
The present invention relates to the technical field of control apparatus for industrial sewing machines and more particularly to an electronic device for autosetting control in industrial sewing machines comprising a microprocessor control unit provided with a nonvolatile storage and respective key-controlled panel. Through said keys, it is possible to key in the values of the control parameters for the operation of the differential feed dog, the main feed dog and upper feed dog or of the presser foot and the tension group, acting on an equal number of actuator means respectively.
2. Prior Art
It is known that in the field of textile machines the automatization of all production processes has not yet been achieved.
In greater detail in the field of industrial sewing machines the possibility of changing the machine setting for the different types of workings is becoming increasingly more necessary. That is to say it is often necessary to modify the position and/or operation of some elements of the sewing machine depending upon the type of workpiece to be sewn and the working cycle to be performed thereon.
Said elements consist for example of the differential feed dog, the main feed dog, the upper feed dog or the presser foot and the tension group.
The differential feed dog is an element which by an elliptical movement performs the function of shirring or stretching the fabric being worked depending upon the cases, acting in synchronism with the main feed dog designed to define the stitch length. The differential and main feed dogs operate through the workpiece supporting table under the workpiece to cause the latter to move forward along the supporting table.
The upper feed dog is a further element cooperating with the differential and main feed dogs to assist the forward movement of the workpiece. The presser foot is a plate-like element acting upon the workpiece to ensure the grasping and pulling action of the differential and main feed dogs.
Finally, the tension group essentially consists of a number of take-up members each of them engaging one of the needle threads to cause the appropriate tensioning thereof.
At the present state of the art, these members are manually adjusted by means of adjustment screw means and/or linkages fixed to predetermined positions by suitable locking fingers. In greater detail, the elliptical movement of the differential and main feed dogs can be adjusted by linkages allowing the adjustment of the respective strokes. On the contrary the upper feed dog movements and the load on the presser foot are adjusted by acting on threaded fits connected to a drive rod.
Each of said take-up members can be in turn be adjusted by acting on a threaded finger to vary the preloading of a spring acting on dish-shaped elements between which the needle threads pass.
As previously said, all the above adjustments can be achieved only manually and therefore they involve long down times each time the machine must be set for a new working cycle.
It is also to be noted that in many cases the machine setting needs the intervention of a skilled person, which increases the service costs.